Printing surface and process of producing the same



E. LANKES Feb. 4, 1930.

Filed June 2s, 1928 INVENTOR;

- Attorney.

Patented Feb. 4, 1930 PATENT OFFICE EDUAR'D LANKES, OF MUNICH, GERMANYPRINTING SURFACE AND PROCESS OF PRODUCING THE SAME Application filedJune 23, 1928, Serial No. 287,880, and in Germany April 11, 1927.

The invention relates to a printing surface and improvements in theprocess of producing the same, by impressing a picture on the side of asheet having its surface coated with f 5 chalk or prepared clay andwashing or etch- 15 which reduces the labour and expense, and

produces a thinner sheet, suitable for use in rotary and platen pressesof substantial power, but it is found that the solution of chloride oflime used for washing or etching,

- to produce the relief, penetrates the sheet l and destroys it.

My invention consists substantially of a relief printing surface formedby a sheet, coated on one side only with a chalk or clay preparation.The back of the sheet is protected from the action of the solvent oretching liquid by impregnation or by application of a protectivecoating. For this purpose I may use a hardener, such as formaldehyde, or

an inorganic hardening salt, or the like, with animal glue or casein asbindingagent.l The chalk or clay is preferably applied in the form ofthin successive layers.

This treatment of the back of the sheet tends also to prevent thecurling of the sheet.

The inventionV is illustrated in the accompanying drawing which shows atransverse section of the improved plate. In the drawing, a denotes asheet of paper material or the like having one of its surfaces providedwith a coating b of chalk or clay preparation and its opposite surfaceprovided4 with a coating o resistant to any liquid capable of removingthe substance of the coating b.

The etching of a plate such as that shown in the drawing is effected asfollows: The entire plate is immersed in the etching fluid so that notonly the chalk or clay coated side but also the rear side is subject tothe action of the etching fluid. The chalk'or clay coated surface isetched by the fluid and, unless the rear side of the plate wereprotected, it also would be attacked by the fluid, making the paperbrittle and interfering with proper registry. As shown in the drawing,the rear side of the plate is provided with the resistant coating c, andunder these conditions when the plate as a whole is immersed in theetching fluid and repeatedly turned therein as is usually done, thechalk or clay treated surface is properly etched while the oppositesurface which is protected by the resist c is unaffected by the etchingfluid, so that destruction of the paper and rolling up of the plate areprevented, and no trouble with registration is encountered.

What I claim is l. Mechanical relief printing surface, consisting of asheet of paper coated on one side only with a chalk or clay preparationrelief, characterized by the fact that the uncoated side of the sheet isprotected from the action of the solvent or etching liquid by aprotected coating which remains permanently in place and prevents thesheet from curling.

2. Process of producing a printing surface, consisting in coating oneside only of a sheet of paper with prepared chalk or clay, applying tothe uncoated side of the sheet a material which remains permanently inplace and renders the sheet resistant to a washing or etching liquidcapable of removing the chalk or clay and which material also preventsthe sheet from curling, impressing a picture on the side of the sheetcoated with chalk or clay and washing or etching away the chalk or claynot covered by the impression of the picture.

3. A mechanical relief printing surface as claimed in claim l, in whichthe protective coating consists of a hardener and animal glue as abinding agent.

4. A mechanical relief printing surface as claimed in claim'. l, inwhich the protective ctliating consists offormaldehyde andanimal g ue;

In testimony whereof I hereunto affix my signature.

EDUARD LANKES.

